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A confederated AS is comprised of three members. One member is comprised of 4 routers, while the other two members are comprised of 3 routers each. Assuming member ASs are fully meshed and use full mesh iBGP, what is the required number of BGP sessions within the confederation?
Suggested Answer: D
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39 comments · newest first
FL
Flo
10 months ago
Definitely 15 sessions, trust me on this!
DO
Dorothy
10 months ago
No way, it should be 14!
KR
Kris
10 months ago
I think it's 12 sessions, right?
LO
Lorrine
11 months ago
Wait, how do we even get to that number?
CH
Cherri
11 months ago
There are 10 routers total in the confederation.
RO
Roosevelt
11 months ago
I feel like the total sessions should add up from each AS, but I can't remember if we need to account for any overlaps. I hope I got this right!
EL
Elvera
11 months ago
If I recall correctly, for a full mesh, the formula is n(n-1)/2 for each AS, but I’m a bit confused about how to combine them in a confederation.
SH
Shad
11 months ago
I think we need to consider the number of routers in each AS and then calculate the sessions for each member. It feels similar to a practice question we did on full mesh iBGP.
CH
Christene
12 months ago
I remember something about calculating BGP sessions based on the number of routers, but I'm not sure how to apply it here with the confederation setup.
CA
Carey
12 months ago
Alright, time to put pen to paper and work through this systematically. I'm feeling more confident now that I've heard a few different approaches.
PE
Pete
1 year ago
I think I've got it! For a full mesh iBGP, each router needs a session with every other router. So the total number of sessions should be the sum of the number of sessions for each member AS.
LU
Luisa
1 year ago
I'm a bit confused on how the full mesh iBGP comes into play here. Gotta make sure I understand that concept before I can solve this.
MA
Mabelle
1 year ago
Okay, let me break this down step-by-step. We have 3 member ASs, with 4, 3, and 3 routers respectively. That's 10 routers total.
EL
Eladia
1 year ago
Hmm, this looks like a tricky one. I'll need to think through the iBGP full mesh requirements carefully.
LE
Levi
2 years ago
Because each router in the fully meshed member ASs needs to establish a session with every router in the other member ASs, so it's 4 routers x 3 routers + 3 routers x 3 routers = 12 + 9 = 21. But since iBGP sessions are not required within the same member AS, we subtract 7 (3 routers x 2 sessions) to get 14.
LI
Lizbeth
2 years ago
Why do you think it's 14?
RY
Ryann
2 years ago
I feel like I need a diagram to visualize this. Or maybe a cup of coffee to help me focus. Either way, I'm going to give this my best shot.
AL
Alisha
1 year ago
D) 15
JI
Jin
1 year ago
C) 14
VI
Vicky
1 year ago
B) 13
VE
Vernell
1 year ago
A) 12
MA
Maybelle
1 year ago
D) 15
AN
Annmarie
1 year ago
C) 14
AS
Ashlee
1 year ago
B) 13
SH
Sheridan
2 years ago
A) 12
CL
Claudio
2 years ago
C) 14
LA
Laticia
2 years ago
B) 13
VA
Val
2 years ago
A) 12
LE
Levi
2 years ago
I disagree, I believe the answer is C) 14.
JO
Jose
2 years ago
Haha, this question is like a game of connect the dots, but with routers instead of, well, dots. I'm going with D, just to see if I can beat the system!
AL
Alberta
2 years ago
Okay, let's think this through. If each member AS is fully meshed, that means we have 4 + 3 + 3 = 10 routers, and each router needs to connect to every other router, so that's a lot of sessions.
KA
Kara
1 year ago
C) 14
FA
Fabiola
2 years ago
B) 13
JE
Jesusa
2 years ago
A) 12
LI
Lizbeth
2 years ago
I think the answer is A) 12.
TA
Tamesha
2 years ago
Wait, do we have to count the routers or the BGP sessions? I'm so confused!
DE
Deeanna
2 years ago
User 3: Yes, that's correct. The required number of BGP sessions within the confederation is 12.
HE
Henriette
2 years ago
User 2: Oh, I see. So the answer would be 12 then.
AB
Abel
2 years ago
User 1: You have to count the BGP sessions, not the routers.